Signaling extended functionality and management information in a network

ABSTRACT

A technique is disclosed for conveying extended functionality control and management information in networks. Enhanced stations encode the control and management information in pre-existing messages. In accordance with the illustrative embodiment of the present invention, the enhanced stations perform the encoding without the need to create nonstandard or proprietary frame formats. Unenhanced stations that are present in the same network as enhanced stations react to the encoded information in a benign way.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 60/491,342, filed Jul. 30, 2003, entitled “Use of OUI to ConveyInformation in a Wireless Network,” which is herein incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to telecommunications in general, and,more particularly, to local area networks (LAN).

BACKGROUND OF THE INVENTION

FIG. 1 depicts a schematic diagram of wireless local-area network (LAN)100 in the prior art. Wireless local-area network 100 comprises stations102-1 through 102-K, wherein K is a positive integer, andshared-communications channel 103. Stations 102-1 through 102-K aretypically associated with host computers (not shown), such as notebookcomputers, personal digital assistants (PDA), tablet PCs, etc. Stations102-1 through 102-K enable communications between (i) the host computersor (ii) the host computers and other devices, such as printer servers,email servers, file servers, etc.

Stations 102-k, for k=1 through K, transmit data blocks called “frames”over shared-communications channel 103. If two or more stations transmitframes simultaneously, then those frame transmissions can interfere witheach other, resulting in what is called a “collision”. Local-areanetworks, therefore, typically employ a medium access control (MAC)protocol for ensuring that a station can gain exclusive access toshared-communications channel 103 for an interval of time in order totransmit one or more frames. A “protocol” is a set of communicationsprocedures that relate to the format and timing of transmissions betweendifferent stations.

In wireless local-area networks that are based on the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard, the mediumaccess control protocol is based on a mechanism called “carrier sensemultiple access” (CSMA), in which station 102-k can detect whethershared-communications channel 103 is busy or idle. Ifshared-communications channel 103 is busy, station 102-k will wait untilthe channel is idle before attempting to transmit a signal that conveysa frame. Meanwhile, station 102-k monitors shared-communications channel103 and reads the address information contained in each transmittedframe to determine if another station is transmitting a frame to station102-k.

Protocols that are based on a specific standard, such as IEEE 802.11,comprise a standard set of functions, as well as the messages thatsupport those functions. All stations that are built to a specificstandard use the messages in that standard so that those stations areable to understand each other. As long as all stations in the samenetwork (e.g., network 100, etc.) are built to the same standard, theycan all understand each other.

Sometimes, it is desirable to add enhanced functionality to at leastsome of the stations in a network. For example, a network operator oruser might want some of the stations in the network to control eachother or exchange data in an enhanced way. Often the added functionalityrequires that stations communicate additional information to each other.The difficulty in adding functionality to a standardized protocol isthat once the standard has been ratified—and manufactured to—it isextremely difficult, if not impossible, to change the standardizedprotocol to accommodate the added functions.

Therefore, the need exists for a way of conveying extended functionalitycontrol and management information without some of the disadvantages andcosts in the prior art.

SUMMARY OF THE INVENTION

The present invention is a technique for signaling extendedfunctionality and management information in an existing network withoutsome of the disadvantages and costs in the prior art. In theillustrative embodiment of the present invention, enhanced stationsconvey information to each other through the use of specially-encodedmedium access control (MAC) layer addresses. Each specially-encodedaddress comprises a first address subfield and a second addresssubfield. The first address subfield represents a specific set ofcontrol functions, and the second address subfield represents a specificcontrol function within the set specified by the first address subfield.

The specially-encoded address is conveyed by a message from a commonmessage set (e.g., IEEE 802.11, etc.). Using a common message ensuresbasic compatibility, in that all stations, both enhanced and unenhanced,at least reads the address contained in the message. Each unenhancedstation, upon not recognizing the address as its own, correctly behavesaccording to the protocol of the common message set. A control frame, inparticular, can be used to convey the address field because (i) controlframes are short, thereby minimizing the impact on network performance,and (ii) stations interpret control frames in a benign way.

In some embodiments, the first address subfield is associated with anorganizationally unique identifier (OUI) that, in turn, represents aspecific set of control functions. The organizationally uniqueidentifier is registered with an overseeing agency, such as the IEEE, sothat no two organizations use the same organizationally uniqueidentifier for their own, different purposes. The organizationallyunique identifier is regarded as a universally-administered address,which means that a specific lot of enhanced stations can be programmedand then used to support the specific control function set, either inthe same network or in multiple networks that all require the sameenhanced functionality.

The technique in the illustrative embodiment of the present invention isminimally-impacting on station operations. Network operators cantypically pre-configure a group address matching table within anenhanced station to monitor for a particular address value or range ofvalues. The monitoring can occur regardless of whether or not thelower-level hardware or firmware of the stations is aware of anyspecific function indicated in second address subfield of arrivingframes. When a match occurs between the value in an arriving frame andthe value stored in the group address matching table, the station passesat least a portion of the arrived frame to higher-level firmware orsoftware or both. The higher-level processing can then handle thespecific function or functions that are signaled in the second addresssubfield, independent of the lower-level processing in the station.

The technique in the illustrative embodiment of the present invention isalso minimally-impacting on network operations. Network operators canchoose to add or swap in enhanced stations in a network that already hasunenhanced stations. Network operators can also start with only enhancedstations in a network and add unenhanced stations, if a need to do soexists. The technique maintains compatibility in a mixed network.

An illustrative embodiment of the present invention comprises: (a)receiving via a shared-communications channel a first message thatcomprises an address field, wherein: (i) the address field comprises afirst address subfield and a second address subfield, and (ii) thecontent of the first address subfield is associated with a specificcontrol function set; and (b) decoding information in the second addresssubfield, wherein the decoding of the information is based on thespecific control function set.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic diagram of wireless local area network 100 inthe prior art.

FIG. 2 depicts a schematic diagram of a portion of network 200 inaccordance with the illustrative embodiment of the present invention.

FIG. 3 depicts a block diagram of the salient components of enhancedstation 203-m in accordance with the illustrative embodiment of thepresent invention.

FIG. 4 depicts address field 400 in accordance with the illustrativeembodiment of the present invention.

FIG. 5 depicts a flowchart of the salient tasks performed in accordancewith the illustrative embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 2 depicts a schematic diagram of network 200 in accordance with theillustrative embodiment of the present invention. Network 200 comprisesunenhanced stations (or simply “stations”) 202-1 through 202-L, whereinL is a positive integer; enhanced stations 203-1 through 203-M, whereinM is a positive integer; host computers 204-1 through 202-P, wherein Pis a positive integer equal to L plus M; and wirelessshared-communications channel 205, interconnected as shown. In someembodiments, network 200 is a wireless local area network.

Stations 202-1 through 202-L and enhanced stations 203-1 through 203-Moperate in accordance with an IEEE 802.11 standard. It will be clear,however, to those skilled in the art, after reading this specification,how to make and use embodiments of the present invention that operate inaccordance with other protocols. Furthermore, it will be clear to thoseskilled in the art, after reading this specification, how to make anduse embodiments of the present invention that use a wireline or tangibleshared-communications channel.

Station 202-i, where i is between 1 and L, inclusive, comprises a radiothat enables host computer 204-i to communicate with other devices viashared-communications channel 205. Station 202-i is capable of receivingdata blocks from host computer 204-i and transmitting overshared-communications channel 205 messages (e.g., frames, packets, etc.)that comprise the data received from host computer 204-i. Station 202-iis also capable of receiving messages via shared-communications channel205 that originate from other devices and sending to host computer 204-idata blocks that comprise data from the messages. It will be clear tothose skilled in the art how to make and use station 202-i.

Enhanced station 203-m, where m is between 1 and M, inclusive, comprisesa radio that enables host computer 204-(m+L) to communicate with otherdevices via shared-communications channel 205. As a device will addedcapability relative to station 202-i, enhanced station 203-m processesdata blocks in accordance with the illustrative embodiment of thepresent invention. Enhanced station 203-m is capable of receiving datablocks from host computer 204-(m+L) and transmitting overshared-communications channel 205 messages (e.g., frames, packets, etc.)that comprise the data received from host computer 204-(m+L). Enhancedstation 203-m is also capable of receiving messages viashared-communications channel 205 that originate from other devices andsending to host computer 204-(m+L) data blocks that comprise data fromthe messages. The salient details for enhanced station 203-m aredescribed below and with respect to FIG. 3. It will be clear to thoseskilled in the art, after reading this specification, how to make anduse enhanced station 203-m.

Host computer 204-p, where p is between 1 and P, inclusive, is capableof generating data blocks and transmitting those data blocks to station202-p or enhanced station 203-j, where j is equal to (p−L). Hostcomputer 204-p is also capable of receiving data blocks from station202-p or enhanced station 203-j, and of processing and using the datacontained within those data blocks. Host computer 204-p can be, forexample, a desktop or a laptop computer that uses network 200 tocommunicate with other hosts and devices. It will be clear to thoseskilled in the art how to make and use host computer 204-p.

(Unenhanced) stations 202-i, for i=1 through L, and enhanced stations203-m, for m=1 through M, communicate directly with each other, inaccordance with the illustrative embodiment. The stations are able tocommunicate with each other in various combinations (i.e., unenhancedstation-to-unenhanced station, unenhanced station-to-enhanced station,enhanced station-to-enhanced station, and enhanced station-to-unenhancedstation). In other embodiments, communications between stations passthrough an access point. It will be clear to those skilled in the arthow to make and use an access point.

Because station 202-i is unenhanced, any communication that involves atleast one station 202-i occurs by using a common message set of standardmessages. Standard messages include a data frame, a control frame, amaintenance frame, etc. All stations that constitute network 200 use thesame version of IEEE 802.11 (e.g., 802.11b, etc.) and, therefore, usethe common message set associated with that version of IEEE 802.11.

FIG. 3 depicts a block diagram of the salient components of enhancedstation 203-m in accordance with the illustrative embodiment of thepresent invention. Enhanced station 203-m comprises receiver 301,processor 302, memory 303, and transmitter 304, interconnected as shown.

Receiver 301 is a circuit that is capable of receiving messages fromshared-communications channel 205, in well-known fashion, and offorwarding them to processor 302. It will be clear to those skilled inthe art how to make and use receiver 301.

Processor 302 is a general-purpose processor that is capable ofperforming the tasks described below and with respect to FIGS. 4 and 5.It will be clear to those skilled in the art, after reading thisspecification, how to make and use processor 302.

Memory 303 is capable of storing programs and data used by processor302. It will be clear to those skilled in the art how to make and usememory 303.

Transmitter 304 is a circuit that is capable of receiving messages fromprocessor 302, in well-known fashion, and of transmitting them onshared-communications channel 205. It will be clear to those skilled inthe art how to make and use transmitter 304.

An example now follows, in which enhanced station 203-1 and enhancedstation 203-2 communicate with each other as part of the local-areanetwork of ACME, Inc., a fictitious organization.

Enhanced stations 203-1 and 203-2 communicate with each other by usingone or more encoded messages, each of which comprise an address field,as is known in the art. The address field comprises a destinationaddress of the station that will deliver at least a portion of themessage to higher protocol layers for processing. One example of adestination address is a 48-bit medium access control [MAC] layeraddress, as is known in the art. It will be clear to those skilled inthe art how to represent a value that is treated by other stations as adestination address by using the address field.

The encoded message appears superficially to unenhanced stations 202-i,for i=1 through L, to be a standard message that belongs to the commonmessage set of network 200. Station 202-i monitors shared-communicationschannel 205, in well-known fashion, for messages that are addressed tostation 202-i. During the monitoring activity, station 202-i detects theencoded message, checks the address field of the encoded message, anddetermines that the message is not intended for station 202-i.

The address field, referred to as an “info-address,” comprises subfieldsthat are depicted in FIG. 4 and used in accordance with the illustrativeembodiment of the present invention. FIG. 4 depicts address field 400that comprises:

-   -   i) I/G indicator 401, an indicator of an individual or a group        address;    -   ii) U/L indicator 402, an indicator of a universally or locally        administered address;    -   iii) first address subfield 403; and    -   iv) second address subfield 404.

I/G indicator 401 is set to indicate a “group” address, as is known inthe art. The group that is referred to in this context comprisesmultiple stations. The group address indication signifies that addressfield 400 is directed at more than one station (i.e., is a “multicast”address). The group in the example comprises enhanced stations 203-m,for m=1 through M.

Upon detecting that a group address is indicated in an arriving frame,all receiving stations, both enhanced and unenhanced, compare theaddress field value with their known group address lists that have beenstored in a matching table, in well-known fashion. When a match occursbetween the value in an arriving frame and a value stored in the groupaddress matching table, the station then acts on control informationthat is encoded in the frame.

In other embodiments, I/G indicator 401 indicates without ambiguity an“individual” address (as opposed to a “group” address). One situation inwhich an individual address can be used is where the encoded controlinformation is used in a frame that is a sole or final frame of asequence of frames. The sole or final frame is often a control frame(e.g., clear_to_send, etc.). Sometimes, group addresses are disallowedin control frames, making an individual address preferred, if notnecessary.

U/L indicator 402 is set to indicate a universally-administered address.An address that is registered with an overseeing agency (e.g., the IEEE,etc.) is an example of a universally administered address.Universally-administered addresses are intended to ensure that the sameaddress encoding is not used to represent different applications.

First address subfield 403 depicted in FIG. 4 represents a controlfunction set. The control function set, in accordance with theillustrative embodiment, comprises one or more functions that aresupported by enhanced stations 203-m, for m=1 through M, but not bystations 202-i, for i=1 through L. When first address subfield 403indicates a specific control function, the receiving station recognizesthat the transmitting station is invoking extended functionality orconveying management information or both.

In some embodiments, first address subfield 403 represents a 22-bitorganizationally unique identifier (OUI). The organizationally uniqueidentifier is registered for a particular application and forms thebasis for the uniqueness of medium access control layer addresses.Organizationally unique identifiers are registered with an overseeingagency (e.g., the IEEE, etc.) that universally administers theidentifiers.

Second address subfield 404 depicted in FIG. 4 is used to indicate aspecific function to the destination station. The specific functionindicated is part of the control function set indicated in first addresssubfield 403. In some embodiments, second address subfield 404 is 24bits long.

Second address subfield 404, in some embodiments, also conveysinformation that indicates the intended recipient of the frame. This isparticularly important in networks where multiple enhanced stationsexist, but where there is only one intended recipient of a given frame.For example, second address subfield 404 can convey at least a portionthe receiving enhanced station's medium access control layer address. Itwill be clear to those skilled in the art, after reading thisspecification, how to encode information as part of second addresssubfield 404 to indicate an intended recipient.

The relationship between first address subfield 403 and second addresssubfield 404 in address field 400 is further explained here. ACME, Inc.,the fictitious organization in the example, requires that some of thestations on its local area network be enhanced with added functionalitythat allows those enhanced stations to share information in a specific,non-standard way. ACME's enhanced stations are programmed to recognizethat the specific control function set that is represented by firstaddress subfield 403 corresponds to the added functionality. One of theexemplary functions that is used by enhanced station 203-1 is theability to request restricted data from enhanced station 203-2 that onlyenhanced stations may share. That specific control function (i.e., “giveme special data”) is specified in second address subfield 404, alongwith an identifier of enhanced station 203-2.

It will be clear to those skilled in the art, after reading thisspecification, how to make and use other control functions, in additionto requesting data as in the previous example.

FIG. 5 depicts a flowchart of the salient tasks performed in accordancewith the illustrative embodiment of the present invention.

At task 501, enhanced station 203-1 transmits into shared-communicationschannel 205 a first message. In the example, the first message is aclear_to_send frame, as is known in the art. The clear_to_send frame iscategorized as a control frame in the standard message set of theprotocol in use. Of particular importance is that the clear_to_sendframe used in this way serves mainly as a conveyance of the encodedaddress field information. Station 203-1 uses a clear_to_send frame, asopposed to some other frames, because it is benign to unenhancedstations.

In the example provided, the first message specifies a data request, asdescriber earlier. It will be clear to those skilled in the art how totransmit a message into shared-communications channel 205.

At task 502, enhanced station 203-2 receives the first message viashared-communications channel 205. It will be clear to those skilled inthe art how to receive a message via shared-communications channel 205.

At task 503, enhanced station 203-2 decodes the content of the firstaddress subfield of the received first message. It will be clear tothose skilled in the art, after reading this specification, how todecode the information in the first address subfield.

At task 504, enhanced station 203-2 determines that the first addresssubfield represents a specific control function set—that is, ACME,Inc.'s control function set. It will be clear to those skilled in theart, after reading this specification, how to determine that the firstaddress subfield represents a specific control function set.

At task 505, enhanced station 203-2 decodes the information in thesecond address subfield within the address field of the received firstmessage. Enhanced station 203-2 decodes the information based on thespecific control function set indicated in the first subfield. It willbe clear to those skilled in the art, after reading this specification,how to decode the information in the second address subfield. In theexample provided, enhanced station 203-2 determines that the functionthat is represented by the second address subfield corresponds to arequest to transmit data back to the requesting station (i.e., enhancedstation 203-1).

At task 506, enhanced station 203-2 transmits into shared-communicationschannel 205 a second message based on the decoded information in thesecond address subfield of the first message. The second message mightor might not indicate an extended control function, that is, it might bepurely a standard message, such as a data frame with a standard mediumaccess control layer destination address that corresponds to enhancedstation 203-1. It will be clear to those skilled in the art, afterreading this specification, how to format and transmit the secondmessage.

In other embodiments, enhanced station 203-2 performs another function(e.g., turns itself off, etc.) in response to having received the firstmessage.

At task 507, enhanced station 203-1 receives the second message inwell-known fashion.

Network 200 can support than one control function set for more than oneapplication on the same network. It will be clear to those skilled inthe art, after reading this specification, how to make and use networksthat use multiple control function sets or multiple functions within agiven set or both.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by those skilled in the artwithout departing from the scope of the invention. For example, in thisSpecification, numerous specific details are provided in order toprovide a thorough description and understanding of the illustrativeembodiments of the present invention. Those skilled in the art willrecognize, however, that the invention can be practiced without one ormore of those details, or with other methods, materials, components,etc.

Furthermore, in some instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the illustrative embodiments. It is understood that thevarious embodiments shown in the Figures are illustrative, and are notnecessarily drawn to scale. Reference throughout the specification to“one embodiment” or “an embodiment” or “some embodiments” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment(s) is included in at least one embodimentof the present invention, but not necessarily all embodiments.Consequently, the appearances of the phrase “in one embodiment,” “in anembodiment,” or “in some embodiments” in various places throughout theSpecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, materials, orcharacteristics can be combined in any suitable manner in one or moreembodiments. It is therefore intended that such variations be includedwithin the scope of the following claims and their equivalents.

1. A method for providing enhanced functionality in a shared-medium network comprising: receiving, at a first device from a second device, via a shared-communications channel a first message that comprises a destination address field containing an address different from an address of the first device, wherein: said destination address field comprises a first address subfield and a second address subfield, and the content of said first address subfield indicates a specific requested control function set that defines a predetermined set of one or more functions; decoding information in the first address subfield to determine the specific control function set requested; determining, at a first protocol layer, that the specific control function set requested is available at the first device; and passing at least a portion of the content of the second address field to a higher-protocol layer for processing, wherein the information from the second address subfield determines at least one function selected from the one or more functions associated with the specific control function set to be processed at the higher-protocol layer.
 2. The method of claim 1, further comprising transmitting a second message from the first device to the second device, wherein the content of said second message is a result of the at least one function determined by the information from the second address subfield.
 3. The method of claim 1, wherein the first message is formatted in accordance with an IEEE 802.11 protocol.
 4. The method of claim 1, wherein the first protocol layer is a Medium Access Control (MAC) protocol layer and the destination address field is a Medium Access Control (MAC) protocol layer physical address; and wherein the content of said first address subfield is associated with an organizationally unique identifier that uniquely identifies a control function set in the shared-medium network.
 5. The method of claim 3, wherein said first message is a control frame consistent with the IEEE 802.11 protocol.
 6. An apparatus configured to provide enhanced functionality in a shared-medium network, the apparatus comprising: a receiver for receiving a first message from a second device via a shared-communications channel, the first message comprising a destination address field containing an address different from an address of the receiver, wherein: said destination address field comprises a first address subfield and a second address subfield, and the content of said first address subfield indicates a specific requested control function set that defines a predetermined set of one or more functions; a processor configured to decode information in said first address subfield to determine the specific control function set requested, to determine at a first protocol layer that the requested specific control function set requested is available, and passing at least a portion of the content of the second address field to a higher-protocol layer for processing, wherein the information from the second address subfield determines at least one function selected from the one or more functions associated with the specific control function set to be processed at the higher-protocol layer.
 7. The apparatus of claim 6, further comprising a transmitter for transmitting a second message to the second device, wherein the transmitting of said second message includes a result determined by the at least one function requested by the information from the second address subfield.
 8. The apparatus of claim 6, wherein the first message is formatted in accordance with an IEEE 802.11 protocol.
 9. The apparatus of claim 6, wherein the first protocol layer is a Medium Access Control (MAC) protocol layer and the destination address field is a Medium Access Control (MAC) protocol layer physical address; and wherein the content of said first address subfield is associated with an organizationally unique identifier that uniquely identifies a control function set in the shared-medium network.
 10. The apparatus of claim 8, wherein said first message is a control frame consistent with the IEEE 802.11 protocol.
 11. A method for obtaining the services of an enhanced functionality device in a shared-medium network comprising: generating a first message that comprises a Medium Access Control (MAC) protocol layer physical destination address field containing an address different from an address of the enhanced functionality device, wherein: said destination address field comprises a first address subfield and a second address subfield, said first address subfield contains content indicating a requested specific control function set that defines a predetermined set of one or more functions; and said second address subfield contains content identifying at least one function selected from the one or more functions associated with the specific control function set; encoding information in said first and second address subfields, wherein the encoding of said information is based respectively on said specific control function set and said at least one function; and transmitting the first message via a shared-communications channel to the enhanced functionality device that supports the predetermined set of one or more functions.
 12. The method of claim 11, further comprising receiving a second message from the second enhanced functionality device, wherein the second message contains information responsive to said at least one function.
 13. The method of claim 11, wherein the first message is formatted in accordance with an IEEE 802.11 protocol.
 14. The method of claim 11, wherein the content of said first address subfield is associated with an organizationally unique identifier that uniquely identifies a control function set in the shared-medium network.
 15. The method of claim 13, wherein said first message is a control frame consistent with the IEEE 802.11 protocol.
 16. The method of claim 5, wherein the content of the first message indicates one or more functions not supported by the IEEE 802.11 standard.
 17. The apparatus of claim 8, wherein the content of the first message indicates one or more functions not supported by the IEEE 802.11 standard.
 18. The method of claim 13, wherein the content of the first message indicates one or more functions not supported by the IEEE 802.11 standard.
 19. The method of claim 1, wherein the first protocol layer is a Medium Access Control (MAC) protocol layer and the destination address field is a Medium Access Control (MAC) protocol layer physical address.
 20. The method of claim 1, wherein the first and second devices are endpoint devices in the shared medium network.
 21. The apparatus of claim 6, wherein the first protocol layer is a Medium Access Control (MAC) protocol layer and the destination address field is a Medium Access Control (MAC) protocol layer physical address.
 22. The apparatus of claim 6, wherein the apparatus is an endpoint device in the shared medium network.
 23. An apparatus configured to obtain the services of an enhanced functionality device in a shared-medium network comprising: a transmitter for transmitting a first message to the enhanced functionality device via a shared-communications channel, the first message comprising a destination Medium Access Control (MAC) protocol layer physical address field containing an address different from an address of the enhanced functionality device, wherein: said destination address field comprises a first address subfield and a second address subfield, said first address subfield contains content indicating a requested specific control function set that defines a predetermined set of one or more functions; and said second address subfield contains content identifying at least one function selected from the one or more functions associated with the specific control function set; a processor configured to encode information in said first and second address subfields, wherein the encoding of said information is based respectively on said specific control function set and said at least one function, and to cause the transmitter to transmit the first message containing the encoded information to the enhanced functionality device that supports the predetermined set of one or more functions.
 24. The apparatus of claim 23, further comprising a receiver for receiving a second message from the second enhanced functionality device, wherein the second message contains information responsive to said at least one function.
 25. The apparatus of claim 23, wherein the first message is formatted in accordance with an IEEE 802.11 protocol.
 26. The apparatus of claim 23, wherein the content of said first address subfield is associated with an organizationally unique identifier that uniquely identifies a control function set in the shared-medium network.
 27. The apparatus of claim 23, wherein said first message is a control frame consistent with the IEEE 802.11 protocol.
 28. The apparatus of claim 25, wherein the content of the first message indicates one or more functions not supported by the IEEE 802.11 standard.
 29. The apparatus of claim 23, wherein the apparatus is an endpoint device in the shared medium network.
 30. The method of claim 1, wherein the step of determining that the specific control function set requested is available at the first device comprises the first device comparing the contents of the destination address field to a known address list representing supported function sets and determining that at least one address from the known address list matches the contents of the destination address field.
 31. The apparatus of claim 6, wherein the processor is configured to determine that the requested specific control function set requested is available by comparing the contents of the destination address field to a known address list representing supported function sets and determining that at least one address from the known address list matches the contents of the destination address field.
 32. The method of claim 11, wherein said step of generating the first message further comprises setting an individual/group indicator field to indicate that the message contains a multicast address.
 33. The apparatus of claim 23, wherein the first message further comprises an individual/group indicator field set to indicate that the message contains a multicast address. 